A US financial regulator the Federal Housing Finance Agency (FHFA) wants the investment bank to make the payment to settle loan mis-selling legal claims, according to reports today.

The demand, which is being resisted by the bank, came as one of its London-based executives was arrested over his involvement in a separate multi-billion pound scandal — the so called “London Whale” trading losses.

Javier Martin-Artajo now faces moves to extradite him to America after he turned himself in to police in his native Madrid yesterday.

He had previously “gone missing” while the FBI sought to question him about alleged fraud offences that carry a penalty of up to 25 years in jail. The 49-year-old high-flier had been apparently enjoying a luxury holiday in Zimbabwe with his British wife Sara Berrow, 50.

Pictures show the couple, who have homes in the Cotswolds and Chelsea, at the five-star Bumi Hills safari hotel by Lake Kariba.

Mr Martin-Artajo has been named as a key figure in the huge losses estimated as high as $6.2 billion built up in 2012 by City-based JPMorgan trader Bruno Iksil, nicknamed the London Whale. Mr Martin-Artajo, who was Mr Iksil’s supervisor in London, has said he expects to be cleared of any wrongdoing and that he has fully cooperated with regulators. He was released after questioning.

JPMorgan, once one of the world’s most respected banks, now faces a swirl of allegations and litigation, including a probe into whether it hired the children of Chinese officials to win business.

The FHFA sued JPMorgan and 17 other banks in 2011 over loans supporting $33 billion (£21 billion) worth of mortgage-backed securities. The suggested settlement would be the biggest single penalty paid by any bank for actions ahead of the crisis.

JPMorgan is said to be prepared to settle but regards the $6 billion figures as excessive, according to the Financial Times.

The bank is being investigated by eight US federal agencies and recently said its legal costs could top its reserves by $6.8 billion (£4.4 billion).

The bank has paid an estimated $7 billion (£4.5 billion) in total fines and settlements in the past two years.